Without a doubt HBO or Showtime,
Why?
-still decent budget
-longer shows (53mins)
-more tighter story lines (13-14 episodes per season)
-more adult in genre... Dollhouse is begging for that (did you see that 1st skirt Eliza wore?)
-more creative control to a directors vision (bet HBO wouldnt ask for a gazzilion rewrites and 7 pilots to get people interested)
Scifi doesnt have the money to make Dollhouse
BBC dont know how to make big production shows without them coming off cheap in some way (Doctor Who for example)
A regular network alternative may be NBC as they seem to recognize longer running shows that rise and fall. Heroes is a great example of this, it got really high numbers and then dwindled big time yet they renew it and its now starting to make a big comeback... i GUARANTEE that fox would not have let heroes get to its 3rd season.
The best alternative is definitely premium cable, it has everything needed for these types of shows. Also, those stating that its got nothing to do with the network, it all comes down to numbers seem to understand very little about the problem that exists here... If a show falls short of expectations as a pilot, that comes down 90% on the advertising campaign (you think people didn't like the show after not seeing it?). It also stems from expectations and the way networks pick shows based on a continual growth of fanbase or demanding instant hits.
I should make the point though that the only reason Dollhouse exists is because FOX gave Eliza freedom to make a show and she met up with Joss to create this. Without FOX, we wouldnt have SOOOO many great shows on the air right now and for that reason FOX will be may favourite station, even if i lose respect for them on certain issues.